US3764866A - Corona generator - Google Patents

Corona generator Download PDF

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Publication number
US3764866A
US3764866A US00211542A US3764866DA US3764866A US 3764866 A US3764866 A US 3764866A US 00211542 A US00211542 A US 00211542A US 3764866D A US3764866D A US 3764866DA US 3764866 A US3764866 A US 3764866A
Authority
US
United States
Prior art keywords
electrode
wire
tungsten
generator
corona
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00211542A
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English (en)
Inventor
J Bonaventura
R Harshbarger
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Xerox Corp
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Xerox Corp
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Filing date
Publication date
Application filed by Xerox Corp filed Critical Xerox Corp
Application granted granted Critical
Publication of US3764866A publication Critical patent/US3764866A/en
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/02—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices
    • G03G15/0291—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices corona discharge devices, e.g. wires, pointed electrodes, means for cleaning the corona discharge device
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05F—STATIC ELECTRICITY; NATURALLY-OCCURRING ELECTRICITY
    • H05F3/00—Carrying-off electrostatic charges
    • H05F3/04—Carrying-off electrostatic charges by means of spark gaps or other discharge devices

Definitions

  • ABSTRACT A tungsten wire corona generator having a stable coating thereon for providing the generator with an extremely long life and a stable output.
  • this invention relates to an electrical corona generator capable of producing a highly efficient discharge thus is well suited to effectively charge a receiving surface such as a xerographic plate or the like.
  • This novel generator includes a corona emitting wire constructed of a tungsten material and having a surface coating thereon serving to extend the normal life of the generator and to smooth the corona deposited upon the plate receiving surface.
  • a single wire generator generally referred to as a corotron is employed.
  • the efficiency of the corotron is dependent on many factors including the gap distance between the wire and the plate surface, the nature of the generating wire material, the diameter of the wire and other physical features thereof andthe amount of energy supplied to the corona emitter.
  • most corotrons were constructed of platinum or some other precious metal because these materials displayed the ability to deliver uniform constant charging over a long period of time. As a consequence, these prior art devices were relatively expensive to construct and replacement costs were also high.
  • a further object of this invention is to provide a relatively inexpensive corona generator exhibiting a highly stable output and having a relatively long operating life.
  • a still further object of this inventin is to improve the corona generating art.
  • apparatus for charging the surface of a photoconductive plate which includes a corona generating wire, a source of electrical energy being operatively connected to the generating wire to cause the wire to emit a corona discharge, the wire generator being constructed of a tungsten base material having a high temperature oxide coating thereon which is extremely stable and non-spalling within the operating range of the generator.
  • a corona generating device containing a generator wire 25 of the present invention for depositing an electrostatic charge on the surface of a moving photoconductive recording material.
  • Illustrated in the FIGURE is a xerographic plate 10 made up of a photoconductive insulating material I] placed upon a grounded conductive substrate 12 with the plate being arranged to move along a predetermined path of travel in the direction indicated.
  • the corona generating unit generally referred to as 15, is positioned above the plate surface and is arranged to deposit an electrical charge thereon as the plate surface moves in the direction indicated.
  • the corona unit includes a shield member 17 which substantially encloses one or more corona generator wires 25 19.
  • the shield is preferably made up of an electrically conductive material that is placed at a ground potential.
  • a slit 20 or opening is formed in the bottom of the shield opposite the moving photoconductive surface and provides a path by which a flow of ions discharged by the generator are directed towards and deposited upon the moving plate surface.
  • the corona generating wire is connected by suitable means such as electrical connector 21 to a high potential source 23.
  • the corona wire utilized in the present embodiment is connected directly to the positive terminal of the power source whereby a positive ion discharge is placed on the plate surface.
  • the generator is constructed of a fine wire between 0.003 and 0.006 inches in diameter made of a high quality tungsten being 99.95 percent pure.
  • the wire preferably has a strength of about 280,000 psi. minimum and be capable of being elongated 1.4 percent over a 10 inch length when tested by ASTM method F219 (1) utilizing a cross head speed of approximately 1 ii inches per minute.
  • tungsten wire generator of this nature will initially exhibit extremely good corona generating properties.
  • the uniformity of output i.e. the distribution and amount of corona generated by the wire
  • the generator exhibits signs of early electrical breakdown.
  • the reason for this short operating life is thought to be caused by loose randomly dispersed tungsten oxides which form on the wire surface at the relatively low operating temperatures.
  • These low temperature oxides are found to be metastable and correspondingly, cause an unstable discharge to be produced by the generator.
  • the mechanical properties of these low temperature oxides are such that the oxides invariably spall from the wire in an uncontrolled manner further aggravating the problems involved.
  • a substantially pure tungsten wire 18 having the beforementioned properties is chemically cleaned to remove foreign matter and grease from the surface of the wire and the wire stress relieved. Any suitable process commonly known and used in the art can be herein employed.
  • the wire is then placed within an electrical oven and the oven heated to a temperature in excess of 600C in air.
  • a wire having a diameter of approximately 0.0035 inches, when heat treated in this manner for approximately minutes, will be provided with an oxide coating 19 which is between 1.5 and 3.5 microns thick.
  • this coating shows that it is made up of high temperature oxides including W0 W0 and W 0
  • Generating wires produced in this manner have been found to have an extremely stable coating which serves to prevent physical changes in the wire at the operating temperature and provides for an extremely stable output and long operating life.
  • the high temperature oxide coating thus formed is relatively tough and is capable of readily withstanding light scraping with a metallic instrument. Spalling of the coating occurs only when the generator wire is permanently deformed or kinked. In fact, the wire can be bent about a A inch diameter rod without disturbing the coating in any manner.
  • a test fixture was constructed by which the output of the generator could be evaluated and compared to similar generators constructed of other materials.
  • the fixture basically consisted of a rotatably mounted grounded xerographic plate in drum configuration having a corona wire support mounted adjacent thereto for supporting a wire generator transverse to the drum surface.
  • the wire generator was arranged to be electrically coupled to a high power source of electrical energy with the wire being supported above the drum surface at a distance whereby the corotron drew approximately 325 micro amps of current while charging the plate surface to a potential of approximately 800 volts.
  • a thin brass strip was helically wound about the drum so that the strip continually monitored the bare plate current flow between the generator wire and the plate as the drum rotated under the generator.
  • the brass strip was electrically brought out to a recording device by means of a slip ring and the recorder arranged to record data at approximately mm/sec. Under these operating conditions, a bare plate current of approximately 50 micro amps was initially recorded and the amplitude of the current deviation from this initial current reading was graphically registered.
  • a heat treated tungsten wire was placed within the test apparatus and continually operated for a period of approximately 250 hours. Periodic traces of the bare plate current reveal that the output of the heat treated generator remain relatively stable and unchanged over the test period. Subsequent to this test, a second corona generatorpf untreated tungsten wire similar in dimensions to that previously tested was placed within the fixture and an operating current placed thereon. After approximately 25 minutes of operation, the untreated tungsten generator began to produce a non-uniform and unstable output and thereafter the generator continued to electrically fail.
  • a device for emitting a discharge of corona including a tungsten electrode being arranged to emit a corona discharge
  • a coating overlying at least the discharge region of said electrode being formed of a high temperature tungsten oxide that is stable during periods when said electrode is emitting corona whereby a uniform discharge of corona is produced over an extended period of time.
  • the tungsten electrode is formed of a material that is at least 99 percent pure.
  • the oxide formed on said electrode includes the oxides WO and W 0 4.
  • the oxide coating is of a thickness of about or greater than one-half a micron.
  • the method of producing a corona emitting electrode which is capable of producing a stable output over an extended period of time including providing an electrode of relatively pure tungsten,
  • the coating formed on said electrode includes the oxides W0, and W 0 7.
  • said electrode is formed of a tungsten material which is at least 99 percent pure.
  • the method of producing a corona emitting electrode that is capable of producing a stable output over an extended period of time including producing an elongated tungsten wire formed of a relatively pure material

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Cleaning In General (AREA)
US00211542A 1971-12-23 1971-12-23 Corona generator Expired - Lifetime US3764866A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US21154271A 1971-12-23 1971-12-23

Publications (1)

Publication Number Publication Date
US3764866A true US3764866A (en) 1973-10-09

Family

ID=22787361

Family Applications (1)

Application Number Title Priority Date Filing Date
US00211542A Expired - Lifetime US3764866A (en) 1971-12-23 1971-12-23 Corona generator

Country Status (22)

Country Link
US (1) US3764866A (xx)
JP (1) JPS5328099B2 (xx)
AR (1) AR198185A1 (xx)
AT (1) AT325420B (xx)
AU (1) AU467386B2 (xx)
BE (1) BE793227A (xx)
BR (1) BR7208756D0 (xx)
CA (1) CA1095114A (xx)
CH (1) CH553435A (xx)
CS (1) CS168018B2 (xx)
DD (1) DD103068A5 (xx)
DE (1) DE2245679C3 (xx)
ES (1) ES409976A1 (xx)
FI (1) FI57185C (xx)
FR (1) FR2165635A5 (xx)
GB (1) GB1402739A (xx)
IL (1) IL41096A (xx)
IT (1) IT972692B (xx)
NL (1) NL165341C (xx)
SE (1) SE380294B (xx)
SU (1) SU617026A3 (xx)
ZA (1) ZA729029B (xx)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4096543A (en) * 1975-10-25 1978-06-20 Mita Industrial Company, Ltd. Corona discharge device with grid grounded via non-linear bias element
US4110614A (en) * 1976-12-17 1978-08-29 Xerox Corporation Corona device
US4542977A (en) * 1982-09-20 1985-09-24 Konishiroku Photo Industry Co., Ltd. Method and apparatus for separating recording paper from image retaining member
US4837658A (en) * 1988-12-14 1989-06-06 Xerox Corporation Long life corona charging device
US4910637A (en) * 1978-10-23 1990-03-20 Rinoud Hanna Modifying the discharge breakdown
US5028779A (en) * 1984-11-01 1991-07-02 Xerox Corporation Corona charging device
EP1055972A2 (en) * 1999-05-28 2000-11-29 Canon Kabushiki Kaisha Discharge wire, method of manufacturing discharge wire and electrification device
CN104646566A (zh) * 2015-02-04 2015-05-27 安徽意义环保设备有限公司 一种电晕线折弯架

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3789278A (en) * 1972-12-20 1974-01-29 Ibm Corona charging device
US3813549A (en) * 1972-12-26 1974-05-28 Ibm Self-healing electrode for uniform negative corona
GB1554266A (en) * 1975-07-14 1979-10-17 Xerox Corp Corona charging device
NL8101260A (nl) * 1981-03-16 1982-10-18 Oce Nederland Bv Corona-inrichting.
JPS58182659A (ja) * 1982-04-20 1983-10-25 Ricoh Co Ltd 電子写真装置における帯電方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2922883A (en) * 1955-03-03 1960-01-26 Rca Corp Electrostatic charging means and method
US3537914A (en) * 1968-01-19 1970-11-03 Hewlett Packard Co Passivation of thermal conductivity filaments

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2922883A (en) * 1955-03-03 1960-01-26 Rca Corp Electrostatic charging means and method
US3537914A (en) * 1968-01-19 1970-11-03 Hewlett Packard Co Passivation of thermal conductivity filaments

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4096543A (en) * 1975-10-25 1978-06-20 Mita Industrial Company, Ltd. Corona discharge device with grid grounded via non-linear bias element
US4110614A (en) * 1976-12-17 1978-08-29 Xerox Corporation Corona device
US4910637A (en) * 1978-10-23 1990-03-20 Rinoud Hanna Modifying the discharge breakdown
US4542977A (en) * 1982-09-20 1985-09-24 Konishiroku Photo Industry Co., Ltd. Method and apparatus for separating recording paper from image retaining member
US5028779A (en) * 1984-11-01 1991-07-02 Xerox Corporation Corona charging device
US4837658A (en) * 1988-12-14 1989-06-06 Xerox Corporation Long life corona charging device
EP1055972A2 (en) * 1999-05-28 2000-11-29 Canon Kabushiki Kaisha Discharge wire, method of manufacturing discharge wire and electrification device
US6605165B2 (en) * 1999-05-28 2003-08-12 Canon Kabushiki Kaisha Method of manufacturing discharge wire
EP1055972A3 (en) * 1999-05-28 2004-01-14 Canon Kabushiki Kaisha Discharge wire, method of manufacturing discharge wire and electrification device
US6917776B2 (en) 1999-05-28 2005-07-12 Canon Kabushiki Kaisha Discharge wire, method of manufacturing discharge wire and electrification device
CN104646566A (zh) * 2015-02-04 2015-05-27 安徽意义环保设备有限公司 一种电晕线折弯架

Also Published As

Publication number Publication date
SE380294B (sv) 1975-11-03
SU617026A3 (ru) 1978-07-25
AR198185A1 (es) 1974-06-07
CH553435A (de) 1974-08-30
CA1095114A (en) 1981-02-03
NL165341B (nl) 1980-10-15
BE793227A (fr) 1973-06-22
IT972692B (it) 1974-05-31
DE2245679B2 (de) 1977-07-21
AU5032372A (en) 1974-06-20
FI57185B (fi) 1980-02-29
IL41096A (en) 1976-05-31
NL165341C (nl) 1981-03-16
GB1402739A (en) 1975-08-13
JPS4874231A (xx) 1973-10-06
NL7217159A (xx) 1973-06-26
DE2245679A1 (de) 1973-07-05
FR2165635A5 (xx) 1973-08-03
AU467386B2 (en) 1974-06-20
AT325420B (de) 1975-10-27
DD103068A5 (xx) 1974-01-05
ZA729029B (en) 1973-09-26
BR7208756D0 (pt) 1973-09-25
CS168018B2 (xx) 1976-05-28
IL41096A0 (en) 1973-03-30
DE2245679C3 (de) 1980-06-26
ES409976A1 (es) 1976-06-16
JPS5328099B2 (xx) 1978-08-12
FI57185C (fi) 1980-06-10

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